Aug 6, 2014 - Richard B. Ferguson. Univ. of Nebraska ... John Tatarko ...... the historic Sanborn Field as affected by long-term cropping systems. Commun.
Published August 6, 2014
Soil & Water Management & Conservation
Can Cover Crop and Manure Maintain Soil Properties After Stover Removal from Irrigated No-Till Corn? Humberto Blanco-Canqui* Richard B. Ferguson
Univ. of Nebraska Dep. of Agronomy and Horticulture Lincoln, NE 68583
Virginia L. Jin Marty R. Schmer Brian J. Wienhold
Agroecosystem Management Res. Unit USDA-ARS Lincoln, NE 68583
John Tatarko
Engineering and Wind Erosion Res. Unit USDA-ARS Manhattan, KS 66502
Addition of cover crops and animal manure following corn (Zea mays L.) stover removal for expanded uses may mitigate negative soil property effects of stover removal. We studied the short-term (3 yr) cumulative impacts of stover removal with and without winter rye (Secale cereale L.) cover crop or animal manure application on near-surface (0- to 5-cm depth) soil properties under irrigated no-till continuous corn on a Hastings silt loam (fine, smectitic, mesic Udic Argiustolls) ( Manure > Cover (Table 1). Maximum stover removal (63%) increased wind erocrops (Table 1). These results suggest that amelioration practices sion potential. It resulted in a large reduction in dry aggregate tended to reduce the magnitude of adverse effects compared size and stability and an increase in wind erodible fraction across with plots without amelioration practices (Table 1). Results also all treatments (Table 1). Averaged across all amelioration treatappear to suggest that winter rye cover crop may be more effecments, stover removal reduced geometric mean diameter of dry tive than animal manure at reducing wind erosion potential. aggregates 93%, increased erodible fraction sixfold, and reduced The large stover removal-induced reduction in dry aggreaggregate stability 32% compared with plots without stover regate size and stability and increase in wind erodible fraction moval (Table 1). indicate that stover removal degraded near-surface physical Contrasts between no stover removal and stover removal properties and increased the soil’s susceptibility to wind erosion followed with either cover crops or animal manure was signifi(Table 1). Soil aggregates became smaller and weaker after stover cant (Table 1). Stover removal from plots with either cover crop was removed for 3 yr. The small aggregates can be more easily or manure reduced geometric mean diameter of dry aggregates transported by wind, while the weak aggregates can break more 85% (5.5 vs. 36.5 mm), increased wind erodible fraction fivefold easily into small aggregate sizes compared with large and stable aggregates (Kohake et al., 2010). The near-surface degradation of (27.0 vs. 5.0%), and reduced dry aggregate stability 34% (2.9 vs. −1 soil aggregate processes and properties may be partly attributed 4.4 ln J kg ) compared with plots without stover removal. This finding thus indicates that the addition of cover crop or manure to (i) the decrease in SOC due to stover removal as discussed after stover removal did not offset the adverse effects of removal later, (ii) physical disruption due to raindrop and irrigation drop on soil aggregate properties affecting wind erosion. Our study impact, (iii) possible effects of freezing-thawing cycles and wethypothesis stating that cover crop or animal manure could offset ting-drying cycles due to soil exposure to the atmosphere after the negative effects of stover removal on soil properties was not stover removal (Layton et al., 1993), and (iv) some possible mesupported for soil physical properties affecting wind erosion. Use chanical breakdown of aggregates during baling operations. Data of cover crop and manure for 3 yr after stover removal was insuffifrom this short-term study appear to suggest that stover removal cient to offset the soil’s susceptibility to wind erosion after stover at high rates (63%) should probably be avoided in the region to removal (Table 1). reduce wind erosion potential. It is important, however, that although amelioration pracInfiltration, Water-Stable Aggregates, Soil Organic tices did not significantly offset the stover removal effects, they Carbon, Particulate Organic Matter, and pH tended to reduce wind erosion potential. Table 1 shows that mean values of geometric mean diameter of dry aggregates were Stover removal and amelioration practices did not change in the order: Cover crops > Manure > None, while mean values water infiltration rates. Mean cumulative water infiltration across 1372
Soil Science Society of America Journal
Table 2. Statistical analysis of soil properties in the 0- to 2.5-cm depth after 3 yr of stover management under an irrigated no-till continuous corn in south central Nebraska. Different lowercase letters in a column within the same treatment group indicate significant differences. Treatments and their interactions
Mean weight diameter of water-stable aggregates
Soil organic C
Coarse particulate organic matter
Fine particulate organic matter
mm
g kg−1
mg g−1
mg g−1
pH
Amelioration effect Cover crop Manure None
1.49a 1.27ab 1.03b
20.6b 22.7a 19.5b
4.64ab 5.47a 3.86b
11.71b 14.64a 11.09b
6.53ab 6.85a 6.32b
Stover removal effect No removal 63% Removal
1.47a 1.05b
21.9a 20.0b
4.67 4.64
13.05a 11.9b
6.59 6.53
Inorganic fertilizer effect 125 kg N ha-1 200 kg N ha-1
1.44a 1.09b
21.0 20.8
4.91 4.40
10.81 12.15
6.78a 6.35b
Irrigation Amelioration Irrigation ´ amelioration Removal Irrigation ´ removal Amelioration ´ removal Irrigation ´ amelioration ´ removal N rate Irrigation ´ N rate Amelioration ´ N rate Removal ´ N rate Irrigation ´ amelioration ´ N rate Irrigation ´ removal ´ N rate Amelioration ´ removal ´ N rate Irrigation ´ amelioration ´ removal ´ N rate
Statistical significance (P > F) ns ns *** ** ns ns *** ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns
ns† ** ns *** ns ns ns *** ns ns ns ns ns ns ns
ns *** ns * ns ns ns ns ns ns ns ns ns ns ns
ns ** ns ns ns ns ns *** ns ns ns ns ns ns ns
Contrasts of interest and significance level (P > F) (0% Removal + no Amendment) vs. (63% removal + cover crop)
ns
ns
ns
ns
ns
(0% Removal + no amendment) vs. (63% removal + manure)
ns
ns
ns
ns
ns
* Significant at the 0.05 probability level. ** Significant at the 0.01 probability level. *** Significant at the 0.001 probability level. † ns, No significant differences.
all treatments was 20.4 ± 18.5 mm (mean ± SD) in 2 h. This result suggests that stover removal even at a high rate (63%) would not significantly reduce precipitation or irrigation water infiltration within the soil profile. Water infiltration did not decrease in spite of a significant reduction in near-surface aggregate size and stability due to stover removal. The lack of significant changes in water infiltration due to stover removal is encouraging as this hydraulic property is often the result of an integrated effect of all soil properties and processes related to soil structure including macroporosity, compaction, surface sealing, and aggregation within the root zone. Further monitoring of water infiltration
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characteristics with time is needed to ascertain long-term effects of stover removal on soil hydraulic properties. Irrigation level had no significant effects on soil properties (Tables 2 and 3). Amelioration practices affected wet aggregate stability, SOC, and POM fractions only in the 0- to 2.5-cm depth (Tables 2 and 3). Stover removal affected SOC and fine POM only in the 0- to 2.5-cm depth, but it affected wet aggregate stability at both soil depth intervals: 0 to 2.5 cm (Table 2) and 2.5 to 5 cm (Table 3). Nitrogen fertilization also affected wet aggregate stability at both soil depths. Interactions among all study factors were not significant (Table 2 and 3).
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Table 3. Statistical analysis of soil properties in the 2.5- to 5.0-cm depth after 3 yr of stover management under an irrigated notill continuous corn in south central Nebraska. Different lowercase letters in a column within the same treatment group indicate significant differences. Treatments and their interactions
Mean weight diameter Soil organic Coarse particulate of water-stable carbon organic matter aggregates mm
g kg-1
mg g-1
Fine particulate organic matter
pH
mg g-1
Amelioration effect Cover crop Manure None
1.86 1.69 1.66
19.3 18.8 18.8
3.22 3.25 3.14
9.71 10.73 10.29
6.65 6.76 6.55
Stover removal effect No removal 63% Removal
1.90a 1.58b
19.0 18.9
3.04 3.36
10.14 10.34
6.63 6.67
Inorganic fertilizer effect 125 kg N ha-1 200 kg N ha-1
1.87a 1.61b
19.1 18.9
3.17 3.23
11.50 8.99
6.88a 6.43b
Irrigation Amelioration Irrigation ´ amelioration Removal Irrigation ´ removal Amelioration ´ removal Irrigation ´ amelioration ´ removal N rate Irrigation ´ N rate Amelioration ´ N rate Removal ´ N rate Irrigation ´ amelioration ´ N rate Irrigation ´ removal ´ N rate Amelioration ´ removal ´ N rate Irrigation ´ amelioration ´ removal ´ N rate
(0% Removal + no amendment) vs. (63% removal + cover crop) (0% Removal + no amendment) vs. (63% removal + manure) ** Significant at the 0.01 probability level. *** Significant at the 0.001 probability level. † ns, No significant differences.
Cover crop increased wet aggregate stability by 1.4 times in the 0- to 2.5-cm depth, but manure had no effect compared with plots without amelioration practices (Table 2). At the same depth, compared with control, manure application increased SOC by about 1.2 times, coarse POM by 1.4 times, and fine POM by 1.3 times, but cover crop had no effects (Table 2). The benefits of manure application for increasing SOC and POM concentration were expected. Results suggest that cover crop may not rapidly increase SOC and POM concentration, unlike manure application. Stover removal reduced wet aggregate stability by 29% and SOC and fine POM concentration by 9% in the 0- to 2.5-cm depth relative to retained stover, but it did not affect coarse POM (Table 2). Stover removal also reduced wet aggregate sta1374
ns† ns ns ** ns ns ns ** ns ns ns ns ns ns ns
Statistical significance (P > F) ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns
Contrasts of interest and significance level (P > F) ns ns ns ns ns ns
ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns
ns ns ns ns ns ns ns *** ns ns ns ns ns ns ns
ns ns
ns ns
bility by 17% in the 2.5- to 5.0-cm depth compared to retained stover (Table 3). These results suggest that maximum stover removal (63%) can have adverse effects on soil structural properties near the surface. Stover removal and cover crop did not affect soil pH, but manure application resulted in slightly higher pH (6.8) than plots without manure (6.3) in the 0- to 2.5-cm depth (Table 2). Increasing N fertilizer application from 125 to 200 kg N ha−1, however, reduced soil pH by 6% in the 0- to 2.5-cm and 2.5- to 5.0-cm depths. The decrease in soil pH in near-surface layers with inorganic fertilization has been well documented in literature (Biederbeck et al., 1996; Blanco-Canqui et al., 2014). Results suggest that animal manure may be used to increase pH of acidic
Soil Science Society of America Journal
Fig. 1. Relationships among geometric mean diameter of aggregates (GMDA), dry aggregate stability (DAS), wind erodible fraction (WEF), soil organic C (SOC), and fine particulate organic matter (POM) near the soil surface after 3 yr of stover removal from an irrigated no-till continuous corn with and without winter rye cover crop and manure in south central Nebraska.
soils. The liming benefits of cattle manure has been discussed in previous studies (Eghball, 1999). Contrasts between no stover removal and stover removal followed with either cover crop or animal manure was not significant (Table 2 and 3). Thus, differences in wet aggregate stability and concentrations of SOC, POM, and pH between plots without stover removal and plots with removal followed by cover crop or manure were not significant. This finding suggests that unlike results for aggregate properties related to wind erosion, inclusion of cover crop or application of manure after stover removal did ameliorate the negative effects of stover removal on wet aggregate stability, concentrations of SOC, fine POM, and pH. The decrease in SOC, fine POM, and pH due to stover removal was small, and this decrease was offset with the addition of cover crop or animal manure. The greater decrease in wet aggregate stability and SOC and fine POM concentration in the 0- to 2.5-cm depth than in the 2.5- to 5.0-cm depth indicates that stover removal effects on soil properties were stratified and confined to the shallow surface in the short term. Results suggest that high rates of stover removal www.soils.org/publications/sssaj
can have limited adverse effects on water-stable aggregates, SOC, and POM in the short term. The small decrease in wet aggregate stability due to stover removal near the surface may not greatly affect crop production but may increase risks of water erosion if amelioration practices are not used. Results also indicate that stover removal had more consistent effects on soil aggregation than on POM fractions in the 0- to 5-cm depth (Table 2 and 3). An increase in inorganic N application rate from 125 to 200 kg ha−1 reduced wet aggregate stability by 1.3 times in the 0- to 2.5-cm depth (Table 2) and by 1.2 times in the 2.5- to 5.0-cm depth (Table 3). Although differences were numerically small, this finding suggests that high rates of inorganic N application may tend to deteriorate soil structure. Further monitoring is warranted to better understand inorganic N application effects on wet aggregate stability. Some previous studies have suggested that inorganic N may have soil aggregate dispersing agents (Haynes and Naidu, 1998; Fonte et al., 2009).
Correlations Among NearSurface Soil Properties
Across all treatments, the near-surface changes in soil aggregate properties and SOC concentration were interrelated. Geometric mean diameter of dry aggregates was exponentially and strongly correlated with dry aggregate stability (Fig. 1a), indicating that dry aggregate size decreased as aggregates became weaker. As a result, wind erodible fraction (
